OG详解-OG8 数学2 Q12

Choice B is correct. The sine of an acute angle in a right triangle is the ratio of the length of the side opposite that angle to the length of the hypotenuse. The hypotenuse of a right triangle is the side opposite the right angle. In right triangle ABC, side BC is the side opposite angle A and side AB is the hypotenuse. It’s given that the length of side BC is 35 units and the length of side AB is 171 units. Therefore, the value of sinA is 35171​​  .
Choice A is incorrect and may result from conceptual or calculation errors. Choice C is incorrect. This is the ratio of the length of the hypotenuse to the length of the side opposite angle A rather than the ratio of the length of the side opposite angle A to the length of the hypotenuse. Choice D is incorrect. This is the length of the hypotenuse rather than sinA.